perf/fix(v2): more efficient hot reload & consistent filegen (#1950)

* perf(v2): efficient hot reload, consistent generated file

* changelog

* more

packages/docusaurus-utils/src/__tests__/index.test.ts

@@ -15,6 +15,7 @@ import {
   getSubFolder,
   normalizeUrl,
   posixPath,
+  objectWithKeySorted,
 } from '../index';
 
 describe('load utils', () => {
@@ -82,6 +83,41 @@ describe('load utils', () => {
     });
   });
 
+  test('objectWithKeySorted', () => {
+    const obj = {
+      '/docs/adding-blog': '4',
+      '/docs/versioning': '5',
+      '/': '1',
+      '/blog/2018': '3',
+      '/youtube': '7',
+      '/users/en/': '6',
+      '/blog': '2',
+    };
+    expect(objectWithKeySorted(obj)).toMatchInlineSnapshot(`
+      Object {
+        "/": "1",
+        "/blog": "2",
+        "/blog/2018": "3",
+        "/docs/adding-blog": "4",
+        "/docs/versioning": "5",
+        "/users/en/": "6",
+        "/youtube": "7",
+      }
+    `);
+    const obj2 = {
+      b: 'foo',
+      c: 'bar',
+      a: 'baz',
+    };
+    expect(objectWithKeySorted(obj2)).toMatchInlineSnapshot(`
+      Object {
+        "a": "baz",
+        "b": "foo",
+        "c": "bar",
+      }
+    `);
+  });
+
   test('genChunkName', () => {
     const firstAssert = {
       '/docs/adding-blog': 'docs-adding-blog-062',

packages/docusaurus-utils/src/index.ts

@@ -31,6 +31,15 @@ export async function generate(
   }
 }
 
+export function objectWithKeySorted(obj: Object) {
+  // https://github.com/lodash/lodash/issues/1459#issuecomment-253969771
+  return _(obj)
+    .toPairs()
+    .sortBy(0)
+    .fromPairs()
+    .value();
+}
+
 const indexRE = /(^|.*\/)index\.(md|js)$/i;
 const extRE = /\.(md|js)$/;